1. Field
The present application relates generally to sensor arrays, and more particularly to a method and system for determining the electrical signals of individual sensors in large sensor arrays.
2. Related Art
Electrical sensors are widely used for converting a sample space's physical characteristics, such as temperature or electromagnetic radiation, into an electrical signal. Where multiple measurements of a sample space are required, multiple sensors are employed in a sensor array. Measuring the signal of individual sensors is impractical, however, because routing attendant hardware, such as conduit or electrical connection, to each sensor reduces the array's spatial density. Accordingly, to achieve a reduction in the number of conduits or connections within the array area, measuring the sensors' outputs is typically achieved by multiplexing the electrical signals of the individual sensors and then demultiplexing the multiplexed signal to determine the individual sensors' signals.
Time-division multiplexing (“TDM”) is a typical multiplexing method. In TDM, a sample period, or “frame,” is divided into timeslots, each timeslot allocated to a single sensor's electrical signal. For a sensor array with N sensors, the frame is divided into N timeslots and the electrical signal for the first sensor is transmitted in the first timeslot, the electrical signal for the second sensor is transmitted in the second timeslot, and so on. However, the amount of time in TDM for averaging the generally weak electrical signal for each sensor falls as the number of sensors in the array grows. Consequently, the apparent detection noise level grows as the number of sensors in the array grows when using TDM because the noise bandwidth grows. As a result, TDM is impractical for large sensor arrays employing sensors with relatively weak or noisy electrical signals because the correlation between the averaging time of the noise level and the array size effectively limits the number of sensors.
To achieve high resolution and/or accommodate large sample spaces for sensors with weak electrical signals, a sensor array and multiplexing technique is needed where the output noise level does not grow as the array size grows.
In the present application, improved multiplexed sensor arrays are disclosed. In addition, an improved method for determining the electrical signal of individual sensors in sensor arrays is disclosed. This multiplexing technique allows for sensor readout wherein the output noise level does not substantially grow as the array size grows.